Kubernetes

Learn how to add a Kubernetes cluster in StrongDM. Use the Kubernetes resource type in StrongDM to secure and audit access to any self-managed or cloud-hosted Kubernetes API server.

For an overview of the available Kubernetes features and supported platforms, please see our Kubernetes guide.

Overview

This guide describes how to manage access to a Kubernetes cluster via the StrongDM Admin UI. This process involves creating and configuring a new cluster in the Admin UI and checking the connection to your Kubernetes API server.

If you would like to learn more about how to enable automatic resource discovery within your Kubernetes cluster, or use privilege levels to allow users to request various levels of access to the Kubernetes cluster, please read the Kubernetes Discovery and Privilege Levels section to learn more about those features prior to following this configuration guide.

Prerequisites

Ensure that the Kubernetes API server that you are adding to StrongDM is accessible from your StrongDM gateways or relays. See our guide on nodes for more information.

Your gateways or relays must be able to connect to the entry you choose for the hostname. To verify the connection, use the command prompt from the gateway or relay server and type nc -z <HOSTNAME> port. If your server can connect to this hostname, you can proceed.

If you are using kubectl 1.30 and higher, it will attempt to use WebSockets for exec, attach, cp, and port-forward rather than the legacy SPDY protocol. Note that for StrongDM client versions older than version 45.35.0 did not support WebSocket transport at all. We recommend that you upgrade the StrongDM client to version 45.35.0 or higher.

On kubectl 1.36 and later, a known issue in StrongDM's WebSocket proxy can reset these connections before the transfer completes. This is most commonly seen as connection reset by peer when running kubectl cp against multiple files. It affects the current StrongDM client, including 45.35.0 and higher.

Until this issue is resolved, we recommend that you force the legacy SPDY protocol. See Connect to Kubernetes for the end-user instructions.

Resource Configuration in StrongDM

This section provides instructions for adding the resource in either the StrongDM Admin UI, CLI, Terraform provider, or SDKs.

Admin UI

Set up and Manage With the Admin UI

If using the Admin UI to add the resource to StrongDM, use the following steps.

1. Log in to the Admin UI and go to Infrastructure > Clusters.

2. Click the Add Resource button.

3. Select Kubernetes as the Resource Type and set other resource properties to configure how the StrongDM relay connects.

4. Click Create to save the resource.

The Admin UI updates and shows your new cluster in a green or yellow state. Green indicates a successful connection. If it is yellow, click the pencil icon to the right of the server to reopen the Connection Details screen. Then click Diagnostics to determine where the connection is failing.

CLI

Set up and Manage With the CLI

This section provides general steps on how to configure and manage the resource using the StrongDM CLI. For more information and examples, please see the CLI Reference documentation.

1. In your terminal or Command Prompt, log in to StrongDM:

   sdm login

2. Run sdm admin clusters add kubernetes --help to view the help text for the command, which shows you how to use the command and what options (properties) are available. Note which properties are required and collect the values for them.

   NAME:
      sdm admin clusters add k8s - create Kubernetes cluster
   
   USAGE:
      sdm admin clusters add k8s [command options] <name>
   
   OPTIONS:
      --allow-resource-role-bypass                 (For legacy orgs) allows users to fallback to the existing authentication mode (Leased Credential or Identity Set) when a resource role is not provided.
      --bind-interface value                       IP address on which to listen for connections to this resource on clients. Specify "default", "loopback", or "vnm" to automatically allocate an available address from the corresponding IP range configured in the organization. (default: "default")
      --certificate-authority value                (secret)
      --client-certificate value                   (secret)
      --client-key value                           (secret)
      --discovery-enabled                          Enable discovery for the cluster.
      --discovery-username value                   The user to impersonate in the cluster when running discovery. Required if the cluster is configured for identity aliases. (conditional)
      --egress-filter value                        apply filter to select egress nodes e.g. 'field:name tag:key=value ...'
      --healthcheck-namespace default              This path will be used to check the health of your connection.  Defaults to default.
      --hostname value                             (required)
      --identity-alias-healthcheck-username value  (conditional)
      --identity-set-id value                      
      --identity-set-name value                    set the identity set by name
      --port value                                 (required) (default: 443)
      --port-override value                        Port on which to listen for connections to this resource on clients. Specify "-1" to automatically allocate an available port. (default: -1)
      --proxy-cluster-id value                     proxy cluster id
      --secret-store-id value                      secret store id
      --subdomain value, --bind-subdomain value    DNS subdomain through which this resource may be accessed on clients (e.g. "app-prod" allows the resource to be accessed as "app-prod.<your-org-name>.<sdm-proxy-domain>"). Only applicable to HTTP-based resources or resources using virtual networking mode.
      --tags value                                 tags e.g. 'key=value,...'
      --template, -t                               display a JSON template
      --timeout value                              set time limit for command

3. Then run sdm admin clusters add kubernetes <RESOURCE_NAME> and set all required properties with their values. For example:

   sdm admin clusters add k8s "k8s-cluster-prod"
     --hostname "k8s-prod01.acme.internal"
     --port 443
     --certificate-authority "/etc/strongdm/certs/k8s-ca.crt"
     --client-certificate "/etc/strongdm/certs/k8s-client.crt"
     --client-key "/etc/strongdm/certs/k8s-client.key"
     --identity-set-name "K8s Cluster Admins"
     --identity-alias-healthcheck-username "svc_k8s_health"
     --discovery-enabled
     --discovery-username "sdm-discovery"
     --healthcheck-namespace "default"
     --bind-interface "default"
     --port-override -1
     --egress-filter 'field:name tag:env=prod tag:region=us-west'
     --proxy-cluster-id "plc_0123456789abcdef"
     --secret-store-id "ss_abcdef0123456789"
     --subdomain "k8s-prod01"
     --tags "env=prod,platform=kubernetes,auth=cert,team=devops"
     --timeout 30

4. Check that the resource has been added. The output of the following command should show the resource's name:

   sdm admin clusters list

Terraform

Set up and Manage With Terraform

This section provides an example of how to configure and manage the resource using the Terraform provider. For more information and examples, please see the Terraform provider documentation.

# Install StrongDM provider
terraform {
  required_providers {
    sdm = {
      source  = "strongdm/sdm"
      version = "16.5.0"
    }
  }
}

# Configure StrongDM provider
provider "sdm" {
  # Add API access key and secret key from the Admin UI
  api_access_key = "njjSn...5hM"
  api_secret_key = "ziG...="
}

# Create Kubernetes cluster
resource "sdm_resource" "k8s_cluster_prod" {
  k8s {
    # Required
    name     = "k8s-cluster-prod"                           # <name>
    hostname = "k8s-prod01.acme.internal"                   # --hostname
    port     = 443                                           # --port (default 443)

    # TLS / client auth (recommended: use secret store)
    certificate_authority = file("/etc/strongdm/certs/k8s-ca.crt")      # --certificate-authority
    client_certificate     = file("/etc/strongdm/certs/k8s-client.crt") # --client-certificate
    client_key             = file("/etc/strongdm/certs/k8s-client.key") # --client-key

    # Identity & discovery
    identity_set_name                   = "K8s Cluster Admins" # --identity-set-name
    identity_alias_healthcheck_username = "svc_k8s_health"     # --identity-alias-healthcheck-username (conditional)
    discovery_enabled                   = true                 # --discovery-enabled
    discovery_username                  = "sdm-discovery"      # --discovery-username
    healthcheck_namespace               = "default"            # --healthcheck-namespace

    # Common networking options
    bind_interface = "default"                                 # --bind-interface ("default" | "loopback" | "vnm")
    port_override  = -1                                        # --port-override (-1 = auto-allocate)
    egress_filter  = "field:name tag:env=prod tag:region=us-west" # --egress-filter
    subdomain      = "k8s-prod01"                              # --subdomain / --bind-subdomain (for VN access)

    # Optional integrations
    proxy_cluster_id = "plc_0123456789abcdef"                  # --proxy-cluster-id
    secret_store_id  = "ss_abcdef0123456789"                   # --secret-store-id (recommended for keys/certs)

    # (Legacy orgs) allow fallback auth when no resource role is provided
    allow_resource_role_bypass = false                         # --allow-resource-role-bypass

    # Tags
    tags = {                                                   # --tags
      env      = "prod"
      platform = "kubernetes"
      auth     = "mtls"
      team     = "devops"
    }
  }
}

SDKs

Set up and Manage With SDKs

In addition to the Admin UI, CLI, and Terraform, you may configure and manage your resource with any of the following SDK options: Go, Java, Python, and Ruby. Please see the following references for more information and examples.

Go	​pkg.go.dev​	​strongdm-sdk-go​	​Go SDK Examples​
Java	​javadoc​	​strongdm-sdk-java​	​Java SDK Examples​
Python	​pdocs​	​strongdm-sdk-python​	​Python SDK Examples​
Ruby	​RubyDoc​	​strongdm-sdk-ruby​	​Ruby SDK Examples​

Resource properties

The Kubernetes cluster type has the following properties.

Property	Requirement	Description
Display Name	Required	Meaningful name to display the resource throughout StrongDM; exclude special characters like quotes (") or angle brackets (< or >)
Resource Type	Required	Kubernetes
Proxy Cluster	Required	Defaults to "None (use gateways)"; if using proxy clusters, select the appropriate cluster to proxy traffic to this resource
Hostname	Required	Hostname or IP address of the Kubernetes API server, such as api.kubernetes.example.com; relay server should be able to connect to your Kubernetes API server
Port	Required	Port to connect to the API server; default port value 443
Connectivity Mode	Required	Select either Virtual Networking Mode, which lets users connect to the resource with a software-defined, IP-based network; or Loopback Mode, which allows users to connect to the resource using the local loopback adapter in their operating system; this field is shown if Virtual Networking Mode enabled for your organization
IP Address	Optional	If Virtual Networking Mode is the selected connectivity mode, an IP address value in the configured Virtual Networking Mode subnet in the organization network settings; if Loopback Mode is the selected connectivity mode, an IP address value in the configured Loopback IP range in the organization network settings (by default, 127.0.0.1); if not specified, an available IP address in the configured IP address space for the selected connectivity mode will be automatically assigned; this field is shown if Virtual Networking Mode and/or multi-loopback mode is enabled for your organization
Port Override	Optional	If Virtual Networking Mode is the selected connectivity mode, a port value between 1 and 65535 that is not already in use by another resource with the same IP address; if Loopback Mode is the selected connectivity mode, a port value between 1024 to 64999 that is not already in use by another resource with the same IP address; when left empty with Virtual Networking Mode, the system assigns the default port to this resource; when left empty for Loopback Mode, an available port that is not already in use by another resource is assigned; preferred port also can be modified later from the Port Overrides settings
DNS	Optional	If Virtual Networking Mode is the selected connectivity mode, a unique hostname alias for this resource; when set, causes the desktop app to display this resource's human-readable DNS name (for example, k8s.my-organization-name) instead of the bind address that includes IP address and port (for example, 100.64.100.100:5432)
Secret Store	Optional	Credential store location; defaults to none (credentials are stored in StrongDM resource configuration); to learn more, see Secret Store options
Server CA	Optional	Pasted server certificate (plaintext or Base64-encoded), or imported PEM file; you can either generate the server certificate on the API server or get it in Base64 format from your existing Kubernetes configuration (kubeconfig) file
Client Certificate	Optional	Pasted client certificate (plaintext or Base64-encoded), or imported PEM file; you can either generate the client certificate on the API server or get it in Base64 format from your existing Kubernetes configuration (kubeconfig) file
Client Key	Optional	Pasted client key (plaintext or Base64-encoded) or imported PEM file; you can either generate the client key on the API server or get it in Base64 format from your existing Kubernetes configuration (kubeconfig) file
Healthcheck Namespace	Optional	If enabled for your organization, the namespace used for the resource healthcheck; defaults to default if empty; supplied credentials must have the rights to perform one of the following kubectl commands in the specified namespace: get pods, get deployments, or describe namespace
Enable Resource Discovery	Optional	Enables automatic discovery within this cluster
Authentication	Required	Authentication method to access the cluster; select either Leased Credential (default) or Identity Aliases (to use the Identity Aliases of StrongDM users to access the cluster)
Identity Set	Required	Displays if Authentication is set to Identity Aliases; select an Identity Set name from the list
Healthcheck Username	Required	If Authentication is set to Identity Aliases, the username that should be used to verify StrongDM's connection to it; username must already exist on the target cluster
Resource Tags	Optional	Resource Tags consisting of key-value pairs <KEY>=<VALUE> (for example, env=dev)

Display name

Some Kubernetes management interfaces, such as Visual Studio Code, do not function properly with cluster names containing spaces. If you run into problems, please choose a Display Name without spaces.

Client credentials

When your users connect to this cluster via StrongDM, they have exactly the same rights as the user associated with these keys. Make sure to consider this prior to setup.

Server CA

How to get the Server CA from your kubeconfig file:

1. Open the CLI and type cat ~/.kube/config to view the contents of the file.

2. In the file, under - cluster, copy the certificate-authority-data value. That is the server certificate in Base64 encoding.

  - cluster:
    certificate-authority-data: ... SERVER CERT BASE64 ...

Client certificate

How to get the Client Certificate from your kubeconfig file:

1. From the CLI, type cat ~/.kube/config to view the contents of the file.

2. In the file, under - name, copy the client-certificate-data value. That is the client certificate in Base64 encoding.

  - name: clusterUser_StrongDM_example
    user:
    client-certificate-data: ... CLIENT CERT BASE64...

Client key

How to get the Client Key from your kubeconfig file:

1. Open the CLI and type cat ~/.kube/config to view the file.

2. In the file, under - name, copy the client-key-data value. That is the client private key in Base64 encoding.

  - name: clusterUser_StrongDM_example
    user:
    client-key-data: ... CLIENT PRIVATE KEY BASE64...

Secret Store

By default, server credentials are stored in StrongDM. However, these credentials can also be saved in a secrets management tool.

Non-StrongDM options appear in the Secret Store dropdown if they are created under Settings > Secrets Management. When you select another Secret Store type, its unique properties display. For more details, see Configure Secret Store Integrations.

Test the Connection

1. After creating the Kubernetes cluster resource in the Admin UI, navigate to Infrastructure > Clusters and locate your newly added cluster. The health indicator should turn green once connectivity and credentials are validated.

2. On a test client using the StrongDM desktop app or CLI, connect to the cluster and run a basic command such as kubectl get nodes. Confirm the output returns your nodes and the connection is routed via StrongDM.

3. If discovery is enabled, in the Admin UI verify that namespaces, roles, and service accounts appear under the cluster’s Discovery tab. This indicates StrongDM successfully queried the Kubernetes API.

4. If the health status remains red or yellow:

   • Verify the cluster’s hostname, port, and base credentials (CA, client certificate/key) are correct and reachable from your relay or gateway.

   • Check the certificate-authority and client credentials if using mTLS.

   • Confirm the healthcheck_namespace exists and the identity alias or health-check user (if specified) has the permissions to get pods, get deployments, or describe namespace.

   • Review the Diagnostics tab for authentication or network errors.

Once connectivity is verified and you can perform Kubernetes operations successfully, the cluster resource is ready. You can assign roles, apply policies, and monitor access through StrongDM.

Help

If you encounter issues, please consult the StrongDM Help Center.

Be prepared to provide the following information to StrongDM Support, so that they can inspect logs and confirm node and resource health:

• Resource name or ID

• CLI error output or logs

• Node name and region

• Timestamps of failed attempts